Romana is recalled to Gallifrey, but en route the TARDIS is drawn
through a Charged Vacuum Emboitment into another universe, called
E-Space. Landing on the planet Alzarius, the Doctor meets a group of
humans who are trying to rebuild their spacecraft -- which crashlanded
generations ago -- so they can return to their native Terradon. When
Marshmen begin rising from the swamps during the dreaded time of
Mistfall, however, the Doctor realises that there is something amiss on
Alzarius, and begins to unravel a genetic riddle which stretches back
centuries.

Production

Andrew Smith was a teenaged Doctor Who fan who was eager to
establish a career as a writer. He had submitted material to comedy
programmes such as Not The Nine O'Clock News, and in mid-1978 had
offered a storyline called “The Secret Of Cassius” to the
Doctor Who production office. This was rejected by script editor
Anthony Read, but Read was sufficiently impressed with Smith's potential
that he encouraged the young man to continue sending in ideas.

When new Doctor Who script editor Christopher H Bidmead began
reviewing the programme's files in early 1980, his attention was drawn
to another of Smith's contributions, entitled “The Planet That
Slept”. Bidmead was urgently seeking scripts for Doctor
Who's eighteenth season, and he and producer John Nathan-Turner both
wanted to encourage writers new to the show. Despite Smith's youth and
inexperience, Bidmead commissioned him to write the first episode of
“The Planet That Slept” on February 25th.

Christopher Bidmead and Andrew Smith decided to make
evolution an underlying theme of Full
Circle

In Smith's original outline, the adventure involved the TARDIS landing
on the planet Alzarius, where monstrous Marshmen rise from the swamps
during the time of Mistfall. As the Doctor and Romana explore, a space
freighter crashlands on Alzarius, and the time travellers must help its
crew repair the ship while fending off the Marshmen and gigantic
cave-dwelling spiders. They are aided by a young Marshchild, who has
been rejected by the rest of her kind due to her pacifist nature. In the
end, the Marshchild sacrifices herself to keep the Doctor and Romana
safe until the mists vanish and the Marshmen retreat to the swamps.

Bidmead was impressed with the striking images that Smith conjured in
“The Planet That Slept”, but asked him to make several
changes as he fleshed the story out into script form. Bidmead wanted to
give Doctor Who a much stronger scientific underpinning, and so
he and Smith decided to make evolution an underlying theme of “The
Planet That Slept”. The Marshmen, spiders and even the ship's crew
would all be different evolutionary stages of the same creature. The
space freighter had now become a passenger liner which crashlanded on
Alzarius centuries before the start of the story.

Smith also had to integrate elements of a story arc that Bidmead had
conceived, which would begin in “The Planet That Slept” and
run through the next two serials. This had been developed at the
suggestion of fan advisor Ian Levine, who recalled the tighter
continuity between stories sometimes seen in Doctor Who during
the Sixties. For his part, Bidmead wanted to impart more meaning to the
Doctor's seemingly aimless wandering. Nathan-Turner was less keen on
this idea, having witnessed the difficulties that overarching plots had
imposed on Season Sixteen, when every story involved the search for a
segment of the Key To Time. However, he ultimately consented to
Bidmead's notion of a shorter story arc; this concerned the TARDIS
becoming trapped in a pocket universe called E-Space, from which the
Doctor would strive to escape.

Most significantly, however, Smith was asked to introduce a new
companion devised by Nathan-Turner, called Adric. The character had
already been written into State Of Decay,
which would be made before “The Planet That Slept” but
broadcast afterwards. It was decided that Adric would take over some of
the Marshchild's role in the story. Smith also had to include Adric's
brother, who had been called Afrus in Adric's original character
description, but was now renamed Varsh.

Adric took over some of the Marshchild's role in Full Circle

Bidmead worked closely with Smith in preparing the script for the
opening installment of “The Planet That Slept”, and on March
31st the remainder of the story was commissioned. It was now known that
Smith's adventure would be the fourth story into production (and so was
designated Serial 5R) but the third to be screened, after Meglos. Various changes were made during the
scripts' development. A power struggle amongst the Outlers between Varsh
and Tylos was eliminated, while a Marshchild character was reintroduced,
replacing a mature Marshwoman. Lexeter was renamed Dexeter (to avoid
confusion with Lexa in Meglos) while Terradon
was initially spelt “Teradon”. Finally, in mid-June, Bidmead
retitled the serial Full Circle.

Although State Of Decay -- the middle part
of the E-Space trilogy -- had already been recorded, it was not until
June 12th that Bidmead issued a document detailing the story arc. His
idea was that the TARDIS would pass through a Charged Vacuum Emboitment
(or CVE), a region of space-time in which the interaction of matter and
antimatter particles with strong electromagnetic fields has created the
doorway to a number of tiny subsidiary universes. The Doctor and Romana
would then become trapped in such an “exo-space/time
continuum” (dubbed “E-Space”, while the normal
universe was termed “N-Space”) which would register on the
TARDIS controls as having negative coordinates. Because E-Space would be
very small -- containing just two galaxies -- the Doctor would have an
unprecedented ability to steer the TARDIS. In addition to forming the
background for the three E-Space stories, Bidmead planned that these
details would also presage elements of the season's concluding
adventure.

The director assigned to Full Circle was Peter Grimwade, who had
previously worked on Doctor Who as a production assistant dating
back to 1970's Spearhead From Space; he
had come to know Nathan-Turner when both were involved with All
Creatures Great And Small. Grimwade had recently completed the BBC's
internal directors course, and had already worked on an episode of
The Omega Factor. He was also a writer, having contributed to
Z Cars, and had submitted an idea called “Zanadin”
(later Time-Flight) to the Doctor
Who production office which was being considered for the season's
final slot.

Work on Full Circle began with three days on location at Black
Park in Fulmer, Buckinghamshire, from July 23rd to 25th. Waterhouse
rejoined the cast, having not appeared in Meglos. It was only at this stage that the
Alzarians' ability to rapidly heal injuries was introduced; previously,
Adric's knee had been mended by a spray that the Doctor provides. Smith
visited the shoot on the first day, but was unwell and vomited on the
Marshmen costumes.

The Alzarians' ability to rapidly heal injuries was a late
addition to the script

The first studio block for Full Circle occurred on August 7th and
8th in BBC Television Centre Studio 3. The opening day dealt with all of
the interior TARDIS sequences, while the second day was concerned with
material in the Starliner lower decks and corridors, as well as the
cave. The second recording session took place from August 21st to 23rd
in TC6. The rest of the cave scenes were taped on the 21st, along with
those in the Science Unit. The next day, model sequences were shot
alongside material in the Great Book Room. The baby Terradonian was
played by Alys Dyer, the daughter of production unit manager Angela
Smith; she had also been the infant Pangol in The
Leisure Hive earlier that year. Finally, scenes in the
boarding area and corridors of the Starliner were completed on the
23rd.

Additional dialogue recording during post-production on Full
Circle included a mention of Citizen Darchir on the Starliner
tannoy. This was an anagram of “Richard”, referring to
Smith's friend Richard Walter; like Smith, Walter was a member of the
Doctor Who Appreciation Society, and edited its fanzine,
TARDIS. Buoyed by the success of Full Circle, Smith
submitted several further ideas to the Doctor Who production
office. These included “The Torson Triumvirate” later in
1980, and “The First Sontarans” in 1984. However, none of
Smith's ideas were taken forward, and Full Circle wound up being
his only contribution to the series. His subsequent credits included
comedy sketch programmes on both television and radio.

Meanwhile, around the time that Full Circle was in production, it
became clear that Tom Baker would not be returning to Doctor Who
for an eighth season. Baker was already the longest-serving Doctor by
two years, and was becoming visibly tired of the job; he also disagreed
with several of the changes that Nathan-Turner had made to the series,
and did not get along well with Waterhouse. Baker had hinted about
leaving Doctor Who several times in the previous few years, but
it was now clear that both the actor and the production team saw eye to
eye on the situation. The final straw came when Nathan-Turner suggested
that Baker would not be in line for a pay raise for Season Eighteen.
With Baker's imminent departure becoming more and more certain,
Nathan-Turner and Bidmead found themselves planning for a genuine end of
an era...